Study shows an increased risk of Guillain-Barré Syndrome with the J&J vaccine; the estimated observed to expected rate ratio was 4.18 for the 42-day window.

Association of Receipt of the Ad26.COV2.S COVID-19 Vaccine With Presumptive Guillain-Barré Syndrome, February-July 2021 – JAMA

Commentary on Twitter

Study suggests a potential small but statistically significant safety concern for #GuillainBarré syndrome following receipt of the @JanssenUS #COVID19 vaccine; findings considered preliminary pending analysis of medical records to establish a definitive Dx https://t.co/yZjJVkp6BA

— JAMA (@JAMA_current) October 7, 2021